The aim of the study is to investigate the relationship between daytime and night-time mean blood pressure (BP) on carotid artery stiffness (CAS) and wave intensity (WI) in 1) hypertensive patients (pts) and in 2) the subgroups formed according to the circadian patterns of BP.Design and method:
We investigated 148 hypertensive pts, mean age 58 years. The subgroups were created according to the circadian patterns (64 dippers, 56 non-dippers, 14 extreme dippers, 14 reverse dippers). Measurements of CAS and WI were performed on right common carotid artery (CCA) using ultrasound combined with echo-tracking. We analysed stiffness parameters: stiffness index (beta), pressure-strain elasticity modulus (Ep), arterial compliance (AC), augmentation index (AIx) and one-point pulse wave velocity (PWV). Parameters of WI: W1- correlates with the maximum rate of left ventricular pressure; W2 - occurs towards the end of ejection; negative area (NA) - indicates the effects of reflected waves, pre-ejection period (r-W1), ejection period (W1–2), provide the information about ventricular-arterial coupling.Results:
Systolic daytime and night-time mean BP correlated with AIx (r = -0.32, p < 0.0001; r = -0.32, p < 0.0001), with mean CCA diameter (r = 0.30, p < 0.0001; r = 0.37, p < 0.0001) and with mean W1 (r = 0.31, p < 0.0001; r = 0.32, p < 0.0001). Daytime and night-time diastolic BP significantly correlated with AIx. Compared with dippers the stiffness values were higher in non-dippers, but highest in reverse dippers (PWVdipper = 7.2m/s, reverse dipper = 7.9m/s, p = 0.03). Similarly mean diameter was larger in non-dippers and largest in reverse dippers. On the other hand AIx was lower in non-dippers and lowest in reverse dippers. Value r-W1 was lowest in reverse group (r-W1 dipper = 98ms, reverse dipper = 80.5ms, p < 0.01). Differences between the stiffness values in dippers and extreme dippers were statistically not significant.Conclusions:
Relationship between systolic daytime and night-time BP with AIx and W1 may provide information about the impact of BP on wave reflection and ventricular-arterial coupling. The stiffness values were significantly elevated in non-dippers and mainly in reverse dippers.